The Police Association has warned of the likelihood of another mass killing in New Zealand because of the ready availability of semi-automatic weapons.
Parliament's Law and Order Select Committee is holding an inquiry into how, and from where, criminals are getting their hands on firearms
Police Association president Greg O'Connor said new rules should be considered now, in a rational way.
"There probably will be another mass killing of the sort we're seeing regularly overseas, however we are best to do our review of our Firearms Act and firearms regime now without the emotion and political demands that will inevitably follow such a shooting."
He said New Zealand had a relatively lax firearms law.
"It's relatively easy to get hold of semi-automatic rifles, assault rifles of the type which is regularly used overseas and New Zealand tends to follow most other trends."
Mr O'Connor said the problem needed to be identified, before a solution could be found.
"And the problem is currently far too many people in New Zealand have - criminals and others who should never have access to firearms are getting access to firearms relatively easily.
"We need to find out why, and we need to stop it."
Police Minister Judith Collins acknowledged a mass shooting was always a possibility.
"You can't prevent people from lawfully having firearms, who should be able to have them, so I think it's always got to be a balance but I would never rule out the fact that that sort of thing can happen.
"The trouble is you can't arrest everyone before they commit crimes."
Labour's police spokesperson, Stuart Nash, said he did not believe banning some weapons would prevent mass killings.
"What we do know is mental illness is underfunded and obviously it's people with significant mental problems who end up killing people.
"Obviously restricting guns to those sorts of people is a priority and the licensing system does a pretty good job of sorting out who should have a gun licence and who shouldn't."
Mr O'Connor was also pushing for a buy-back of illegal weapons, alongside other measures.
"We need registration but we also need an amnesty and a buy-back to ensure that those firearms that are out will never be collected, or never be registered in a registration scheme, are taken off the street.
Ms Collins said the idea of a buy-back has been brought up before and, if the police wanted one, they could always come to her to talk about it.
But she said she would await the outcome of the inquiry before making any decisions about an amnesty or changes to gun laws.